THERMOSETTING ACRYLIC RESINS which is superior to either alkydmelamine system. Enamel from Resin C is about equal to the coconut alkydmelamine enamel in impact resistance but is much harder and, in general, has better resistance properties then either alkyd finish. I t is more resistant to stains and detergents than the enamel from Resin B, but does not equal the flexibility of the former. Both experimental enamels are significantly harder and more resistant than the enamel from Resin A previously cited. Enamel from Resin B has also been compared to the two conventional alkyd appliance whites in overbake color and gloss retention and shows definite superiority when overbaking for 1 hour at 350” F. The superiority becomes even more marked when testing 1 hour a i 450’ F.
Parts by Weight Epoxidieeda Resin C Oil 90 75 50 a
The usefulness of the acrylamide interpolymers as sole resins in enamels, and when modified with epoxy resin has been illustrated. The following is an example using Resin B with a vinyl chloride copolymer resin (Vinylite VM-
CH). Parts by Weight Titanium dioxide Resin B solution Xylol Vinylite VMCH solution (25% Solids in 1 to 1 isophorone and methyl isobutyl ketone)
This composition calculates to be 70Yo by weight acrylamide interpolymer and 3oY0 by weight vinyl copolymer. An enamel film baked 30 minutes at 300O F. is thermoset, highly adhesive to steel,
Bake 0.5% HaPOa Temp., Minutes O F.
10 25 50
30 30 30
155.0 433.7 23.3 373.0
Sward Hardness
300 300 300
Impact Resistance, Inch-Pound 2 48 48
44 42 Soft
tinplate, and aluminum foil, tough, and flexible. The film is resistant to alkali, acid, and solvents such as alcohols, aromatic naphthas, and ketones. The compatibility of epoxidized oils with acrylamide interpolymer resins was previously mentioned. Resin C is one of the hardest, least flexible interpolymer compositions. The following shows the plasticizing effect of epoxidized oil interblending testing as clear films. With 10% epoxidized oil, there is little or no reduction in the hardness of the film over using the straight interpolymer resin, whereas there is slight improvement in impact resistance. Other features such as light stability of the film would be improved by the addition of the epoxidized oil. When 25Y0to 50% epoxidized oil is used there is a marked improvement in the flexibility of films. From these comparative properties the general adaptability of acrylamide interpolymer resins for industrial finishing has been briefly indicated.
H. A. V O G E L and H. G. BITTLE Pittsburgh Plate Glass Co. Research and Development Center Paint Division Springdale, Pa.
Epoxidieed oil was Admex 710.
Epoxy Resins in Thermosetting Acrylics T H E COATINGS INDUSTRY has experienced several recent trends which have encouraged investigation of thermosetting acrylic resins. Some of these important trends are:
1
Naturally occurring polymers and oils continue to give way to “custombuilt” polymers synthesized from pure, highly reactive monomers and intermediates. e As a result of the raw material suppliers’ very large-scale production economics, synthetic resins and monomers continue their almost yearly downward shift in prices but upward improvement in purity. 0There is a constant trend away from large quantities of volatile, hazardous solvents. Synthetic latexes, watersoluble vehicles, high solids, one-coat enamels, and solventless coatings are the results. 0 I n the finishing industry, an important factor is the further expansion of techniques and materials for coating metals prior to fabrication, so that application and curing conditions can be better controlled. 0 To be consistent with these developments, polymer chemistry is offered new challenges. Now, relatively low molecular weight reactive polymer
“building blocks” are needed. Traditionally, a great Portion of Polymer synthesis has been directed toward achieving highest possible molecular weight without cross linking. I n the newer industrial coatings and plastics chemistry, the molecular weight buildthrough up is done by our cross linking [‘in situ” after the material is applied.
Group I Hydroxylfunctional
U. S.2557266 U. S.2681897 U. S. 2853462 U. S. 2853463
A review of the Chemical Abstracts patent literature u p to April 10, 1960 gives the unlimited number of different polymer building blocks and coreactive cross linkers adaptable to thermosetting For our initial studies, our interest was narrowed to the more recent solventborne thermosetting resin art which in-
Reactive lnterpolymer Patents Group I1 Group I11 Group IV EpoxideN-MethylolCarboxylfunctional functional functional
U. S.28701 16 U. S. 2870117 Belg. 554183 Can. 573728
u. s. 2324739
E;!: ;::;;;
1
U. S. 2604464
{iiitT*;:7y7Y8 U. S.2897174 U. S.2900359 Brit. 590035
Can. 491115 Can. 534002 U. S. 2662870 Can. 534001 JU.S.2798861 \Can. 534261 U. S. 2810706 Can. 569430
{
u. s. 2524432
Group V Miso. U. S. 2604463 Brit. 681031
U. S. 2580901 U. S. 2687405 U. S. 2692876 U. S. 2723971
U. S. 2899404
U. S. 2729625 U. S.2849418
Can. 567165 Brit. 482897
u. s.2857354
U. S. 2866767
U. S. 2868760
VOL. 53, NO. 6
JUNE 1961
463
Epoxy Resins Studied
Designation
Epoxide Equivalent Weight“
Idealized Structure
Viscosity, 260
c.
Color Gardner
0
/\ c-c-c-0-c-c-0-c-c-0-c-c-c
Experimental I
I
C
0
/\
/\
r
Experimental I11
/O\
1
0
c-c--c-0/\
1
I
CCl
,
L D.E.R.b 332
1
CCI
-c-c-0-
c-c-c-0
52 cps.
